5 different apertures. 19 kinds of adjustable corrective lenses; range of lenses: -20D-+20D.<br> The clip with integrated on/ off switch for simple use.<br> Powered by 2xAA batteries (not included), easy to install and replace batteries.<br> Compact size and design for easy storage and convenient transport.<br> Elaborate design and reliable quality. A classic instrument for physician.<br> Illumination: Direct Illumination<br> Luminance: 14 Lumen<br> Bulb: 106 2.5V, 0.5A; 206 3.0V, 0.08A<br> Operation: Temperature 10-35, Humidity 30%-70%, Air Pressure 700hPa-1060hPa<br> Storage & Transport: -20-70, Humidity 10%-90% (without condensation), Air Pressure 500hPa-1060hPa<br> Colour:As Shown<br> Material:ABS+Metal<br> Package Contents:<br> 1 x Eye Checker<br> Only the above package content, other products are not included.<br> Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.